Best place to stay in Bangkok Thailand, (Bang Rak District)?

I am female asian and will be working in Harindhorn Office (54 North Sathorn Rd, Bangkok) soon. I need an advise as where is the best place to stay with a monthly rental budget of 4000 to 6000 THB. In which I can commute using a convenient transpo means (Bus, Train) ? Or walk. I am not sure if motorbike is safe to ride if you're foreigner in Thailand, as I had bad experience before when I tour Bangkok. Thank you.